Electronic bilateral ferrite reflection switch



Oct. 16, 1962 J. L. CARTER ELECTRONIC BILATERAL FERRITE REFLECTION SWITCH Filed March 7, 1960 INVENTOR, JOHN L. CARTER.

M24/7% dwarf@ A TTONEX SQZ Patented ct. 16, 1952 dice 3,059,192 ELECTRGNIC BLATERAL FERRITE REFLECTN SWITCH John L. Carter, Asbury Park, NJ., assigner to the United States of America as represented by the Secretary of the Army Filed Mar. 7, 1960, Ser. No. 13,399 1 Claim. (Ci. 333-7) (Granted under Titie 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.

This invention relates to electronic switching devices wherein microwave energy is switched from one waveguide to another and particularly to such devices wherein ferrite or similar ferromagnetic material is placed in the path of the energy to control it in a specific manner.

The invention achieves the switching operation by imposing upon the flow of energy in a novel sequence, a combination of control devices including phase shifting of the energy wave by specialized coupling means, plane polarizing by the so called Faraday rotation and transitions between rectangular and round waveguide channels.

The structure of the invention makes possible an eX- tremely fast succession of switching cycles up to 20,000 cycles per isecond and the switching is accomplished with a minimum of power consumption.

The device itself consists of two similar composite energy channels closely adjacent to each other. This structure presents four ports two at each end. These ports are rectangular in cross section and are matched to the rectangular waveguide system in which the switch is incorporated.

The above mentioned ports constitute the energy channels for a pair of 3 db short slot couplers wherein a coupling aperture is formed in the common wall between the channels. The inner ends of the aligned coupler ports are interconnected by means of tapered transistions to a pair of short circular cross section waveguides each having a ferrite rod therein.

An electromagnet surrounds the circular waveguides and serves to produce Faraday rotation in the energy wave passing thru the waveguides. The influence of the ferrite, the couplers and the transitions permit the device to exert maximum control of the energy in a novel manner as will be described in detail hereinafter.

It is a primary object of the invention to provide a switching device for microwave energy which is fast acting and efficient in operation.

A further object of the invention is to provide an electronic switch for microwave energy in which a high percentage of total energy input is switched from one channel to another with a minimum consumption of controlling energy.

A further object of the invention is to provide a reciprocal switching device wherein energy traverses ferrite rotators rst in one direction and again in the opposite direction thus reducing the number of parts required to accomplish a total switching operation. A further object of the invention is to provide an electronic switch functioning as a reciprocal device wherein the effectiveness of ferrite materials for controlling energy is used to its fullest capacity.

A still further object of the invention is to provide an efficient and compact switching structure wherein a pair of composite rectangular and round waveguide channels are combined with maximum economy of space and minimum overall length.

Other objects and features of the invention will more fully appear from the following description and will be particularly pointed out in the claim.

To provide a better understanding of the invention a particular embodiment thereof will be described and illustrated in the drawings wherein:

FIG. l is a block diagram of the principal elements of the device.

FIG. 2 is a longitudinal sectional view of the device taken on line 2 2, FIG. 3.

FIG. 3 is a cross sectional view on line 3 3, FIG. 2i.

The block diagram of FIG. 1 shows the operative relationship of the components which make up the device of the invention. Assuming energy, owing from a source at the left, enters one of the two rectangular channels 5. and 6 which are the ports of a 3 db short slot hybrid coupler 7. Energy entering port 5 for example is split by the coupler and its two components enter channels 8 and 9, consisting of waveguides of circular cross section, where the energy is subject to the control of Faraday rotators in the form of ferrite rods. The function of the rods will be described in full hereinafter.

In passing to channels S and 9 the energy first traverses transitions 13 and 14. At the other end of the round waveguides, transitions 17 and 18 from round to rectangular conformation convey energy to a second coupler 10 of the same type as the coupler 7 having a pair of ports 11 and 12 which are matched with and connected to the waveguide system of which the switch of the invention forms a part. The selected path which the energy will follow is dependent upon whether the ferrite rods are or are not magnetized by an electromagnet. Thus switching is accomplished by current fed to the magnet.

The couplers 7 and 10 referred to herein are the specific type known as 3 db short Islot hybrid couplers developed by Riblet.

The detailed structure and function of a specific form of the invention, will now be set forth with reference to FIG. 2 of the drawings.

It is clearly shown in FIG. 2 that the ports 5 and 6 can be and desirably are the energy channels for the hybrid coupler 7. The transitions 13 and 14 interconnect the output of this coupler to the round cross sectional waveguide portions of channels 8 and i9 which receive the two components of energy provided by the coupler. Energy ilowing in these channels flows to transistions 17 and 1S which connect directly to the port-s 11 and 12 of coupler 10. Ports 11 and `12 constitute energy channels for coupler 10 and are matched with and connected to waveguides constituting a part of the system controlled by the switch.

In the circular waveguide sections of channels 8 and 9 ferrite rods 15 and 16 are supported in any desired manner such as by sleeves 20 and 21 made of polyfoam, The sleeves are dimensioned to fit closely in the sections 8 and 9 and receive the ferrite rods within their axial apertures. Polyfoam or like material is used to reduce energy losses. The term polyfoam is applied to materials which are made by blowing air into plastic materials such as polystyrene in liquid form which when solidied presents a spongelike structure. Desirably the ends of the rods are conical in shape tc reduce reflection of energy therefrom.

It will be noted that in the structure shown in FIG. l all of the power conveying channels are in axial alignment and that the elements of the device are completely integrated into the minimum of space and each component is a continuation of its adjacent elements each blending structurally and electrically with its neighbor without intervening instrurnentalities. This closely knit structure lends itself to the requirements of the double channel feature of the invention involving as it does the use of two 3 db hybrid couplers 7 and 10 wherein the common wall 23 having the coupling apertures 24 therein also constitutes a common wall for the ports 5, 6, 11 and 12.

Vtrnay be used as a switching means.

' or otherpabsorption device. v energy passes freely thru the transitions 13, 14, 17 and 18 To eect the switching action, the ferrite members 15 and 16 must be immersed in a magnetic field. As shown in FTG. 2 the field is supplied by an electromagnet 25 the turns of which are Wound about the circular waveguide sectionsthus to produce lmagnetic flux extending parallel to the ow of energy. Y Y The magnet may be energized in any desired manner. A direct current source of power and a manualy switch However to realize theV full capability of the device the magnet is driven by a pulse generating unit 26 having a high repetition rate and controls for adjusting the pulse rate. The output of the pulse generator is connected to the magnet by wires 27.

-Desirably the energy channels are made of dielectric plastic and may be molded to the desired conformation. The inner walls of the channels are silver plated to provide a low impedance conductor. By thus reducing the metal thickness, energy losses are decreased and greater switching speed is attained. The plating is shown at 28 in exaggerated thickness.

For connection between'the switching device and its associated waveguide system, flanges 29 may be formed upon the outer extremities of the coupler members 7 and which may be joined to the flanged ends of waveguides leading to the controlled system components. The latter waveguide may be of conventional construction and made of metal or other suitable material.

The operation of the device is as follows. Assuming a sourceV of microwave energy such as a magnetron is feeding microwave energy to the port 6 and no current is flowing in Ythe magnet V2S. The ferrite members 15 and y16 are therefore demagnetized. Under the above conditions energy will enter the coupler 7 and be divided into two components. One component will pass from left to right thru the transition 13, entering the circular guide in channel 8 and thence to the coupler 10 thru the transition 17. The other energy component will pass thruV the transition 14 entering the circular guide in channel 9 and after passing the transition 18 will enter the coupler 10. v

At this time the energy components will not be acted upon by the ferrite members and 16 but will be phased by the two couplers '7 and 10 in such a manner that the two energy components will reunite'at coupler 10 and pass to the port 11 and thence to a selected loadrdevice. The port 12 may be connected to a dummy load not shown In the above assumed caseV because the plane of polarization established by the rectangular ports 5 and 11 in the one energy channel and the ports 6 and 12 in the other channels are oriented to offer substantially no impedance to the flow of energy.l

Assuming now that the ferrite members 15 and 16 are magnetized and the energy enters the port 6 and the coupler 7, as before, divides the energy into two components which enter the two channels 8 and 9 passing freely thru the transitions 13 and 14. Now, however, the plane of polarization of the energy waves is rotated 90 by the magnetized ferrite members and when it reaches the tranr sitions 17 and 18 it will see a short circuit/and bereflected backward flowing thru the respective channels in a right to left direction. In soY doing the energy wave is again rotated by the ferrite members another 90 which adds to the previous 90 to elect a total of 180 rotation for each energy component. When these rotated components reach the transitions 13 andr14 on their backward excursions their plane of polarization is suchthat they pass freely therethru and again enter the coupler 7 where the energy components are recombined and will enter the part 5. Thus energy incident at port 6 will be switched to port 5.

It should be noted that the energy may be incident at any one of the ports 5, 6, 11 and 12. Since the device is electrically symmetrical switching action will in any case be as above described.

What is claimed is:

A bilateral waveguide switch comprising: rst and second parallel energy channels having a common wall; said first energy channel comprising first and second rectangular end portions, a first circular -rnidportion having an area smaller than said first and second rectangular portions, first and second transition structures connecting said circular mid-portion to said first and second Vrectangular portions respectively, and a first ferrite rod mounted within said -rst circular midportion, said second energy channel comprising third and fourth rectangular end portions, a second circular mid-portion having an area equal to said Vfirst circular midportion, third and fourth transition structures connecting said second circular mid-portion to said third and fourth rectangular end portions respectively; a first 3 db slot aperture cut adjacent to one end of said common wall for electrically coupling said rst rectangular portion to said third rectangular portion; a second 3 db slot aperture cut adjacent to the other end of said common wall for electrically coupling said secondv rectangular portion to said fourth rectangular portion;

" said first and second ienergy channels normally operating in such a manner that energy entering one of said rectangular end portions will divide through one of said 3 db slots into the adjacentrectangular end portion, traverse both channels, recombine through the other of said 3 db slots and leave said switch via the rectangular end portion diagonally opposite the rectangular end portion through which it entered; an electromagnet embracing both said first and second circular mid-portions; said electromagnet having its 'field parallel to the direction of ow of energy through said channels; and a direct-current pulse generator connected to said electromagnet, said pulse generator energizing said electromagnet so as to energize said ferrite rods and cause'90" Faraday rotation which results in reflection back of energy entering any of said rectangular end portions;V said 3 db slots and saidV first and second energy channels operating in such a manner that energy reflected when said ferrite `rods are energized will leave said switch via the rectangular end portion directly adjacent to the rectangular portion through which it entered; said reflected energy being out of phase with the incident energy.

References Cited in the file of this patent UNITED STATES PATENTS Reingold Nov. 28, 1961 

